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[198.48.202.89]) by smtp.gmail.com with ESMTPSA id k24sm1569612qki.11.2021.08.07.18.57.31 (version=TLS1_3 cipher=TLS_AES_256_GCM_SHA384 bits=256/256); Sat, 07 Aug 2021 18:57:31 -0700 (PDT) From: Liam Beguin To: liambeguin@gmail.com, lars@metafoo.de, Michael.Hennerich@analog.com, jic23@kernel.org, charles-antoine.couret@essensium.com, Nuno.Sa@analog.com Cc: linux-kernel@vger.kernel.org, linux-iio@vger.kernel.org, devicetree@vger.kernel.org, robh+dt@kernel.org Subject: [PATCH v5 2/5] iio: adc: ad7949: fix spi messages on non 14-bit controllers Date: Sat, 7 Aug 2021 21:56:56 -0400 Message-Id: <20210808015659.2955443-3-liambeguin@gmail.com> X-Mailer: git-send-email 2.32.0.452.g940fe202adcb In-Reply-To: <20210808015659.2955443-1-liambeguin@gmail.com> References: <20210808015659.2955443-1-liambeguin@gmail.com> MIME-Version: 1.0 Precedence: bulk List-ID: X-Mailing-List: linux-iio@vger.kernel.org From: Liam Beguin This driver supports devices with 14-bit and 16-bit sample sizes. This is not always handled properly by spi controllers and can fail. To work around this limitation, pad samples to 16-bit and split the sample into two 8-bit messages in the event that only 8-bit messages are supported by the controller. Signed-off-by: Liam Beguin --- drivers/iio/adc/ad7949.c | 75 +++++++++++++++++++++++++++++++++------- 1 file changed, 63 insertions(+), 12 deletions(-) diff --git a/drivers/iio/adc/ad7949.c b/drivers/iio/adc/ad7949.c index 937241ee2a22..3f94ae639a44 100644 --- a/drivers/iio/adc/ad7949.c +++ b/drivers/iio/adc/ad7949.c @@ -14,7 +14,6 @@ #include #define AD7949_MASK_TOTAL GENMASK(13, 0) -#define AD7949_CFG_REG_SIZE_BITS 14 /* CFG: Configuration Update */ #define AD7949_CFG_BIT_OVERWRITE BIT(13) @@ -68,9 +67,11 @@ static const struct ad7949_adc_spec ad7949_adc_spec[] = { * @indio_dev: reference to iio structure * @spi: reference to spi structure * @resolution: resolution of the chip + * @bits_per_word: number of bits per SPI word * @cfg: copy of the configuration register * @current_channel: current channel in use * @buffer: buffer to send / receive data to / from device + * @buf8b: be16 buffer to exchange data with the device in 8-bit transfers */ struct ad7949_adc_chip { struct mutex lock; @@ -78,28 +79,46 @@ struct ad7949_adc_chip { struct iio_dev *indio_dev; struct spi_device *spi; u8 resolution; + u8 bits_per_word; u16 cfg; unsigned int current_channel; u16 buffer ____cacheline_aligned; + __be16 buf8b; }; static int ad7949_spi_write_cfg(struct ad7949_adc_chip *ad7949_adc, u16 val, u16 mask) { int ret; - int bits_per_word = ad7949_adc->resolution; - int shift = bits_per_word - AD7949_CFG_REG_SIZE_BITS; struct spi_message msg; struct spi_transfer tx[] = { { - .tx_buf = &ad7949_adc->buffer, .len = 2, - .bits_per_word = bits_per_word, + .bits_per_word = ad7949_adc->bits_per_word, }, }; ad7949_adc->cfg = (val & mask) | (ad7949_adc->cfg & ~mask); - ad7949_adc->buffer = ad7949_adc->cfg << shift; + + switch (ad7949_adc->bits_per_word) { + case 16: + tx[0].tx_buf = &ad7949_adc->buffer; + ad7949_adc->buffer = ad7949_adc->cfg << 2; + break; + case 14: + tx[0].tx_buf = &ad7949_adc->buffer; + ad7949_adc->buffer = ad7949_adc->cfg; + break; + case 8: + /* Here, type is big endian as it must be sent in two transfers */ + tx[0].tx_buf = &ad7949_adc->buf8b; + ad7949_adc->buf8b = cpu_to_be16(ad7949_adc->cfg << 2); + break; + default: + dev_err(&ad7949_adc->indio_dev->dev, "unsupported BPW\n"); + return -EINVAL; + } + spi_message_init_with_transfers(&msg, tx, 1); ret = spi_sync(ad7949_adc->spi, &msg); @@ -116,17 +135,19 @@ static int ad7949_spi_read_channel(struct ad7949_adc_chip *ad7949_adc, int *val, { int ret; int i; - int bits_per_word = ad7949_adc->resolution; - int mask = GENMASK(ad7949_adc->resolution - 1, 0); struct spi_message msg; struct spi_transfer tx[] = { { - .rx_buf = &ad7949_adc->buffer, .len = 2, - .bits_per_word = bits_per_word, + .bits_per_word = ad7949_adc->bits_per_word, }, }; + if (ad7949_adc->bits_per_word == 8) + tx[0].rx_buf = &ad7949_adc->buf8b; + else + tx[0].rx_buf = &ad7949_adc->buffer; + /* * 1: write CFG for sample N and read old data (sample N-2) * 2: if CFG was not changed since sample N-1 then we'll get good data @@ -144,7 +165,6 @@ static int ad7949_spi_read_channel(struct ad7949_adc_chip *ad7949_adc, int *val, } /* 3: write something and read actual data */ - ad7949_adc->buffer = 0; spi_message_init_with_transfers(&msg, tx, 1); ret = spi_sync(ad7949_adc->spi, &msg); if (ret) @@ -158,7 +178,25 @@ static int ad7949_spi_read_channel(struct ad7949_adc_chip *ad7949_adc, int *val, ad7949_adc->current_channel = channel; - *val = ad7949_adc->buffer & mask; + switch (ad7949_adc->bits_per_word) { + case 16: + *val = ad7949_adc->buffer; + /* Shift-out padding bits */ + *val >>= 16 - ad7949_adc->resolution; + break; + case 14: + *val = ad7949_adc->buffer & GENMASK(13, 0); + break; + case 8: + /* Here, type is big endian as data was sent in two transfers */ + *val = be16_to_cpu(ad7949_adc->buf8b); + /* Shift-out padding bits */ + *val >>= 16 - ad7949_adc->resolution; + break; + default: + dev_err(&ad7949_adc->indio_dev->dev, "unsupported BPW\n"); + return -EINVAL; + } return 0; } @@ -266,6 +304,7 @@ static int ad7949_spi_init(struct ad7949_adc_chip *ad7949_adc) static int ad7949_spi_probe(struct spi_device *spi) { + u32 spi_ctrl_mask = spi->controller->bits_per_word_mask; struct device *dev = &spi->dev; const struct ad7949_adc_spec *spec; struct ad7949_adc_chip *ad7949_adc; @@ -292,6 +331,18 @@ static int ad7949_spi_probe(struct spi_device *spi) indio_dev->num_channels = spec->num_channels; ad7949_adc->resolution = spec->resolution; + /* Set SPI bits per word */ + if (spi_ctrl_mask & SPI_BPW_MASK(ad7949_adc->resolution)) { + ad7949_adc->bits_per_word = ad7949_adc->resolution; + } else if (spi_ctrl_mask == SPI_BPW_MASK(16)) { + ad7949_adc->bits_per_word = 16; + } else if (spi_ctrl_mask == SPI_BPW_MASK(8)) { + ad7949_adc->bits_per_word = 8; + } else { + dev_err(dev, "unable to find common BPW with spi controller\n"); + return -EINVAL; + } + ad7949_adc->vref = devm_regulator_get(dev, "vref"); if (IS_ERR(ad7949_adc->vref)) { dev_err(dev, "fail to request regulator\n");